Heat exchange tank



June 13, 1961 A. E. BUSH EIAL HEAT EXCHANGE TANK 2 Sheets-Sheet 1 FiledSept. 21, 1959 3mm hm .2 9 k MS INVENTOR$ N/CKOLA 5 L. VA CANO ALBERT E.BUSH 14 TTORN E 5 June 13, 1961 A. E. BUSH EIAL HEAT EXCHANGE TANK FiledSept. 21, 1959 2 Sheets-Sheet 2 INV NTOR.

E K 1.45 .V/I A/YO HL ER T E. B USH mam/o" HTTORN United rates Patent .0

2,988,334 HEAT EXCHANGE TANK Albert Bush, 5063 Harold Place NE, andNickolas L. Vacano, 3520 Conover St., both of Seattle, Wash.

Filed Sept. 21, 1959, Ser. No. 841,122 8 Claims. (Cl. 257-208) Thisinvention relates to improvements in tanks wherein means is provided forcontrolling the temperature of the contents of the tank. In thefollowing description and explanation, we will refer more particularlyto tanks used in making or processing beer, however, it shall be clearlyunderstood that our new and improved tank design is not limited to usein breweries but the tanks may be used in milk processing, handling ofchemical solutions or any other use wherein it is desired to raise,lower or control the temperature of the contents of the tank duringproc- -essing or storage.

In the present instance, the tanks are approximately 34 'feet long, 12/2 feet wide and 9 /2 feet in height. The particular dimensions are notcritical and may be varied to a substantial extent without departingfrom the teaching of the invention. They are given here only in order toimpart a better understanding of the invention.

The improvements which characterize the present invention are concernedwith the novel arrangement of means for and manner of cooling the wortthat is placed 'in the tank for fermentation. In this instance, thecooling of the tank is effected by circulation of a liquid coolant .incontact with the exterior surfaces of one or more of 'the metal walls ofthe tank as differentiated from the usual flow of a coolant through pipelines or coils located within 'the tank in direct contact with thefermenting wort or been It is a principal object of this invention toprovide a cooling system for tanks wherein direct contact is madebetween the exterior tank walls and a circulated liquid 'coolant by thepassing of the coolant through channels or ducts formed directly on theexterior surfaces of the tank walls and which channels or ducts are ofsuch crosssectional area and cooling surface that the temperature of thecoolant can be higher than in conventional systems because ofcomparatively large volume flow at reduce linear velocity and pressure.

It is also a principal object of this invention to employ the wallstiffening channels or ribs of the tank as the passages through whichthe coolant is circulated so that channels or ribs serve a dual purpose,namely, as structural members and as coolant passages and therebyeliminate the coils which are normally provided on the interior of thetank.

It is a further object of this invention to so design and arrange ordirect the coolant conducting channels that minimum friction betweencoolant and channel walls will be realized, thus providing lowestpossible pressure loss; while at the same time the coolant will becaused to frequently change its direction of flow relative to the tankwalls resulting in desirable and beneficial mixing within the coolantstream.

Yet another object of the invention is to provide a structure forcooling the liquid content of the tank that eliminates the possibilityof the liquid coolant escaping or leaking into the fermenting wort; thisresult being effected by reason of locating the channels or ducts whichcontain the coolant exteriorly of the tank and by employing the metalwalls of the tank as theinside wall forming part of the coolant ducts.

It is a further object of the invention to provide a cooling system forclosed fermentation tanks that is so associated with the tank as toleave its interior entirely clear of any and all obstructions that wouldbe detri- 2,988,334 Patented June 13, 1961 2' mental to easy washing orcleaning of the interior of the tank.

It is also an object of the invention to provide a tank cooling systemin which any size batch or quantity of wort may be readily andeffectively processed. I

In accomplishing the above mentioned and various other objects andadvantages of the present invention, which will become apparent as thisspecification progresses, we have provided the improved details of tankconstruction, the preferred forms of which are illustrated in theaccompanying drawings, wherein:

Fig. 1 is a side view of a fermentation tank embodying the variousimprovements of the present invention therein.

FIG. 2 is the lower end elevation of the tank.

FIG. 3 is an enlarged sectional detail, taken on line 3 3 in FIG. 1.

FIG. 4 is a horizontal sectional view of the tank, taken on the variouslevels of line 4-4 in FIG. 1.

FIG. 5 is an enlarged sectional detail, taken on line 55 in FIG. 1.

FIG. 6 is a horizontal section taken on line 6-6 in FIG. 1.

Referring more in detail to the drawings:

In FIG. 1, the present fermentation tank is designated in its entiretyby reference numeral 10 and it is there shown as being supported for useon a floor surface 11 that has a downward slope whereby the right handend of the tank is lowered below the level of its opposite end in orderto facilitate the drainage of liquid from the tank.

The tank itself, as previously stated, is of substantial size and ofrectangular form. both in cross-section and in longitudinal section, asis evident from its showing in FIGS. 1, 2 and 3. The tank is of weldedsheet metal construction and its opposite sides, top, bottom and endwalls are all joined in rounded corner bends, as has been illustratedquite clearly in FIGS. 3 and 5, at 12, this being to avoid hard to cleancorners. For later explanatory and dmcriptive purposes, the oppositesidewalls of the tank are herein designated, respectively, by numerals13 and 13; the top wall is designated by numeral 14; the bottom wall isdesignated by numeral 15; the rear end Wall, which is shown at the lefthand side in FIG. 1, is designated by numeral 16 and the front end wallis designated by numeral 17. All walls are of sheet steel, which may bestainless steel or the inner surfaces of the walls may be lined oroverlaid with an inert material, such as epoxy resins, glass or thelike. it is normally less expensive to build a tank of mild steel and toline its interior surface with a suitable inert material.

It will be understood that the present. tank, as so constructed, isentirely free of any internal obstructions, breaks or roughness and withall corners rounded so that internal cleaning, washing and drainage canbe readily accomplished. Draining of the tank is greatly facilitated bythe previously mentioned sloping illustrated in FIG. 1 wherein the dashline 11x represents a horizontal plane and 11 is the downwardly slopingfloor line. Also, the bottom wall of the tank is slightly troughed asillustrated best in FIG. 2, so that the contained liquid of thetank willdrain to a longitudinal center line and thento the lower end of thebottom wall.

Although the bottom wall 15 is sloping as described, we desire tomaintain the top wall 14 horizontal. This feature provides that theheight or distance between the contents of the tank and the top isthesame throughout the length of the tank. Therefore, during fermentation,the foam space is of constant height above the liquid level. Anotheradvantage of the horizontal top is that it reduces the required heightof the rear end wall 16 of the tank which results in a saving ofmaterial and cost.

For filling the tank with the wort to be fermented, it

is equipped at its lower end with a filling pipe 20 which is shown inFIG. 1 to be horizontally disposed and to have an upwardly turned innerend portion opening into the tank through its bottom wall at the lowestpoint. This filling pipe 20 also serves as a discharge pipe in emptyingor drawing liquid from the tank. The wort to be fermented is pumped intothe tank and as the filling of the tank takes place, air is ventedtherefrom through a pipe 21 that leads from an opening in the top wall14 at the forward end of the tank. The pipe 21 is also the means ofwithdrawing the CO gas which is formed by the formentation and forinjection of compressed air after emptying of the liquid from the tank.The pipe is connected to an exhaust or discharge pipe, not shown, forcarrying the gas to a point of discharge into space or for collection.The pipe 22 is a safety vent and connects with a water trap 23. Thesafety vent is to insure that too great a pressure will not be createdin the tank in the event that the discharge of gas through pipe 21becomes obstructed. It also is a safety vent against vacuum beingcreated inthe tank as beer is withdrawn. The tank is normally filledwith wort to approximately 80% of its capacity, that being to slightlymore than three-fourths its depth, however, lesser quantities may beprocessed ii desired. The remaining 20% of the height of the tankprovides space for the produced foam to collect. If the tank is used forstorage, the tank may be filled completely.

The ability to process batches or quantities of any reasonable amount isone of the inherent advantages of our new and improved tank. It will beappreciated that the conventional internal coils are normally positionednear the maximum liquid level of a tank. This requires that the tank befilled to substantially the maximum liquid content for processing andproper cooling. :In our construction the channels extend substantiallyfrom the bottom to the top of the sidewalls so we are able to processany quantity that may be desired.

The cooling system, which is one of the features of the --presentinvention, employs the use of at least a portion of the stiffening orstructural channels on the exterior surfaces of certain walls of thetank and the coolant is circulated through these channels. In thepresent instance, we employ only the channels on the opposite sidewallsfor containing the flowing coolant. However, if desired or required, wemayvutilizethe channels on the top, bottom and end walls. In the presentinstance, it has been found that the cooling of the sidewalls issuflicient. The substantially U-shaped channels, as applied to theopposite sidewalls, are interconnected as shown in FIG. 1.

Each continuous channel is air tight and made up of a succession ofspaced, vertical, hollow stiifening ribs 25 that are secured by weldingdirectly to the exterior of the tank sidewalls. Each rib extends fromnear the bottom to near the top of the wall and in horizontalcrosssection is of substantially quadrilateral form with opopsitesidewalls outwardly converging and so that the rib is wider across thebase than at the outside, as is well shown in FIG. 6.

In FIG. 6, it is to be observed that the sidewall 13 of the tank formsthe base wall of the channel; the opposite sidewalls of the channels aredesignated, respectively, by reference numerals 25a and 25b and theoutside wall by numeral 25c.

Adjacent ribs are joined, alternately, near their lower and upper endsby horizontal channels 26 of cross-sectional form and area similar tothe vertical ribs so that, from end to end, at each side of the tank thejoined ribs provide a continuous channel or duct for the flow of aliquid coolant therein. The channels, as thus provided at opposite sidesof the tank, are interconnected near the end Wall 16 of the tank forcross-flow through a hollow stiffening channel 30 that is appliedtransversely to the underside of the bottom of the tank. This channelbeing constructed similar to the vertical ribs on the 4 sidewalls.Connection of each of the opposite ends of this transverse channel withthe lower ends of the opposite sidewall channels is as shown in FIG. 3wherein it is observed that a pipe '35, formed as a right angle bend, isextended at its ends through the lower end wall 25d of channel 25 andthe adjacent end wall 39a of channel 30 thus to provide for a flow ofliquid coolant from one side of the tank to the other as indicated inthe view by the arrows in the pipe. These connecting pipes at oppositeends of channel 30 are designated in FIG. 4 by numerals and 35'; eachbeing like that shown in FIG. 3.

A removable pipe plug 35a is provided which is applied to the nipple 35bprojecting from the pipe 35. This entrance into the coolant channelprovides means for ascertaining the temperature of the coolant byinsertion of a temperature sensing device at this point.

To permit the venting of air from the channels as they are filled withthe coolant, the ribs 25 are each tapped and plugged at their upper endsas at 36 in FIG. 5. After a substantial quantity of liquidhas beenpumped into the channels, normally to a point above the upper horizontalribs, successive plugs are removed to permit the escapement of entrappedair. Additional liquid is added and venting repeated until substantiallyall of the air is removed from the system. During operation, the plugsmay be removed momentarily to remove any air which may have entered thesystem.

-It has been shown in the several views that the end, top and bottomwalls of the tank are equipped exteriorly with stiffening andstrengthening channels or ribs of a form of construction similar tothose applied to the side walls, but, as was previously stated, theseserve in the present instance for stiffening only and not as coolantchannels. The top wall stiffening ribs are designated by numerals 37 andthose on the opposite end walls by numerals 37 and 37". Also, it isshown in FIG. 1 that stifi'ening webs 38 are applied at the lowerhorizontal corners to tie the ribs 37', 37 to the bottom wall 15.

It is further to be observed, in FIG. 2, that the end wall 17 isprovided centrally, near its lower edge, with a manhole 40 equipped withdoor 41. Entrance to the interior of the tank for cleaning, repair orinspection may be made through this door. The unobstructed interior ofthe tank is quite advantageous for use of mechanized cleaners. It alsoprovides maximum assurance that the tank can be completely and properlycleaned as is absolutely necessary in use of such tanks for fermentationof the wort into beer or for the storage of beer.

In the use of the tank, the wort to be fermented is pumped into the tankthrough pipe 20 to a desired level and the maintaining of the wort atthe proper temperature during its fermenting period is effected bycirculating the selected liquid coolant through the channels provided onopposite sidewalls of the tank. Circulation is effected by a pump, notshown, having discharge and intake connections respectively, with theintake and discharge pipes 42 and 43 that are joined with the channelsat the front end thereof. As the tank is filled with wort or beer, airor gas is exhausted therefrom through the pipe vent 22.

Another detail of construction which provides definite advantages is thepositioning of the horizontal channels 26 above and below, respectively,the lower and upper ends of the vertical ribs 25. Any solid impuritieswhich might enter the coolant system can collect in the lower ends ofthe vertical ribs, below the lower horizontal channels withoutobstructing the flow of the coolant. Any gases or air which might be inthe system can collect in the upper ends of the vertical ribs above theupper horizontal channels. Normally the upper horizontal channels are atliquid level so that most etficient cooling is assured.

In this operation, we prefer to use an aqueous propylene glycol solutionas the coolant liquid, because it does not contain impurities which maysettle in or block the channels or pump, nor is it required that thechannels be frequently cleaned. However, other types of coolant may beemployed if desired.

The cross-sectional area of the channels with their large coolingsurfaces permit circulation of the coolant at a comparatively low linearvelocity and there is repeated change in the direction of flow which isdesirable in controlling the fermentation of wort in that it provides acontinnous stirring or mixing of the coolant in the channel and therebymaintains a substantially uniform temperature of the coolant. The largecross-section also permits high volume flow at low pressure when desiredfor maximum cooling effect.

Also, the use of relatively large channels provides greater structuralstrength for the tank. Further, the large channels minimize pressurebuildup in the coolant system. An increase in pressure could bedestructive to the tank and it would increase the cost of maintainingthe required circulation. It would require internal coils ofsubstantially greater than conventional diameter to accommodate the flowof the same volume of coolant at the same pressure.

As a detail of construction, stifiening and strengthening bars 62 areapplied vertically to the sidewalls of the tank to span the cut-outs inthe sidewalls of the vertical ribs where the horizontal ribs areconnected. The location of these bars is as shown in FIGS. 5 and 6. Thesemicylindrically rounded surfaces of these bars 62 aid in causing asmooth flow and in creating the mixing of the coolant as it flowsthereacross. However, their main purpose is to give strength to thestructure at those particular places.

It is desirable that the entire tank and coolant system are encased in ahousing, preferably a shell of aluminum foil lined with insulation, suchas fiber glass. Such an enclosing casing is designated by referencenumeral 50 in FIGS. 1 and 4, wherein it is indicated in dash lines, andalso in FIGS. 3 and 5 where it is shown in full lines and in section.

The insulating cover minimizes heat loss or any effect on the systemfrom external heat sources. It also reduces exchange of effect betweenadjacent tanks and provides a better overall temperature control. Also,the cover increases the effective cooling area on the walls of the tankbecause in eflect it increases the cooling surface to include theportions of the tank walls between the ribs. The result -is thatsubstantially the entire sidewalls are cooled thus making for greaterefliciency.

As previously mentioned, the temperature of the coolant which we employin our system may be maintained at a substantially higher level than thetemperature of the coolant in a conventional system or structure whereinthe coolant ducts or coils are positioned within the tank. In aconventional internal coil system of lesser cooling surface, thetemperature of the coolant is normally within the range of 10 to 20 F.In our system, we can obtain the desired results with the temperature ofthe coolant maintained between 30 and 32 F., however, higher or lowertemperatures may also be used. The higher temperature reduces coldshocks to the yeast and fermenting wort. The cold shocks are the suddenreductions in temperatures which may occur and which are detrimental tothe action of the yeast. An internal coil accomplishing the same resultwould be large and cumbersome, expensive and lacking the many advantagesdescribed earlier.

To summarize; the present invention provides a less expensive tankconstruction by eliminating the cost of internal cooling coils, moreuniform temperature control during fermentation, the ability to processquantities less than the full capacity of the tank, greater adaptabilityto mechanized cleaning of the tank interior, a completely smoothinterior surface with no attachments or protrusions, no coils on theinterior of the tank to obstruct cleaning, reduced linear velocity ofthe flow of coolant, with accompanying small pressure drop, avoidance ofsharp temperature changes during fermentation, and rapid cooling of thetank contents at full coolant flow.

Our invention is not to be interpreted as limited to any specific tankdesign but is to be understood to include all fermentation, storage andother tanks of any size and shape wherein wall stiffening members areemployed and secured to the exterior surface to strengthen the tankconstruction and wherein the cooling or heating medium is circulatedthrough the stiflening members to provide the required temperaturecontrol.

What we claim as new is:

1. A stationary heat exchange tank for use in processing substantialquantities of fluids, said tank comprising interconnected top and bottomwalls, opposite side walls and opposite end walls, all walls beingjoined to adjacent walls in a fluid tight relationship, the interiorsurfaces of all walls being completely smooth and free of protuberances,a plurality of substantially U-shaped channels vertically disposed andsecured in spaced relationship to the opposite sidewalls, with the freeedges of said channels joined in fluid tight relationship with saidsidewalls, said vertical channels extending substantially the fullheight of the sidewalls, a U-shaped channel extending horizontallybetween each of the adjacent vertical channels, alternate horizontalchannels interconnecting the vertical channels below the upper endsthereof and the remaining horizontal channels interconnecting thevertical channels adjacent the lower ends thereof, said interconnectedvertical and horizontal channels forming a continuous fluid channel, asupply connection for supplying fluid to said continuous channel at oneend thereof, a discharge connection for discharging fluid from saidcontinuous channel, said discharge connection being secured to a channelat the opposite end of the continuous channel.

2. A tank structure as in claim 1 including means interconnect-ing thevertical channels on the opposite sidewalls whereby the entire channelsystem is continuous.

3. A tank structure as in claim 2 wherein there is a single supply and asingle discharge connection for the continuous channel.

4. A tank structure as in claim 1 wherein the horizontal channelsadjacent the upper ends of the vertical channels are positionedsubstantially below the upper ends of said vertical channels whereby anair collection chamber is provided at the upper end of each verticalchannel and means on the upper ends of each of said vertical channelsfor exhausting entrapped air therefrom.

5. A tank structure as in claim 1 including means for venting said tank.

6. A tank structure as in claim 1 including U-shaped channels on theopposite end walls and top and bottom walls.

7. A tank structure as in claim 1 wherein the bottom wall of the tankslopes between the opposite end walls and the top wall of the tank ishorizontal.

8. A tank structure as in claim 1 wherein said bottom wall is in theform of a longitudinal trough and said bottom wall slopes longitudinallybetween the end walls.

Del Mar Feb. 22, 1955 Stover Sept. 24, 1957

